My heart rate drops to 40 when sleeping or sitting for 2-3 hours . i have no other symptoms . i do exercise for about 30 mins daily and during exercise heartbeat reaches to maximum 130 bpm. is it normal?

While a rate of 40 is low since it occurs during sleep and prolonged rest and you have no symptoms, there is nothing to worry about.

It is well-known that “conditioning” occurs in individual who exercise vigorously on regular basis. One consequence of such “conditioning” is a decrease in the resting heart rate. Unless there other abnormalities on examination, reassurance is in order.